Rework parasite code

 - make control block to keep all information
   needed to run injected syscall and parasite
   blobs

 - add ptrace_swap_area helper

 - handle both parasite engine calls and injected
   syscalls by single __parasite_execute function

 - drop jerr() usage

 - bring back handling of inflight signals from
   original program inside parasite code
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>

cr-dump.c

@@ -1225,7 +1225,7 @@ static int dump_one_task(struct pstree_item *item, struct cr_fdset *cr_fdset)
 		goto err;
 	}
 
-	ret = parasite_cure_seized(parasite_ctl, &vma_area_list);
+	ret = parasite_cure_seized(parasite_ctl);
 	if (ret) {
 		pr_err("Can't cure (pid: %d) from parasite\n", pid);
 		goto err;

include/parasite-syscall.h

@@ -17,22 +17,27 @@ struct parasite_ctl {
 	void *			remote_map;
 	void *			local_map;
 	unsigned long		map_length;
+
 	unsigned long		parasite_ip;				/* service routine start ip */
+	user_regs_struct_t	regs_orig;				/* original registers */
+	unsigned long		syscall_ip;				/* entry point of infection */
+	u8			code_orig[BUILTIN_SYSCALL_SIZE];
+	unsigned long		status;
+
 	void *			addr_cmd;				/* addr for command */
 	void *			addr_args;				/* address for arguments */
 };
 
-extern int can_run_syscall(unsigned long ip, unsigned long start, unsigned long end);
-
-extern int parasite_dump_pages_seized(struct parasite_ctl *ctl, struct list_head *vma_area_list,
-			       struct cr_fdset *cr_fdset);
 extern int parasite_dump_sigacts_seized(struct parasite_ctl *ctl, struct cr_fdset *cr_fdset);
 extern int parasite_dump_itimers_seized(struct parasite_ctl *ctl, struct cr_fdset *cr_fdset);
 
 struct parasite_dump_misc;
-extern int parasite_dump_misc_seized(struct parasite_ctl *ctl, struct parasite_dump_misc *);
-
-extern struct parasite_ctl *parasite_infect_seized(pid_t pid, int pid_dir, struct list_head *vma_area_list);
-extern int parasite_cure_seized(struct parasite_ctl *ctl, struct list_head *vma_area_list);
+extern int parasite_dump_misc_seized(struct parasite_ctl *ctl, struct parasite_dump_misc *misc);
+extern int parasite_dump_pages_seized(struct parasite_ctl *ctl,
+				      struct list_head *vma_area_list,
+				      struct cr_fdset *cr_fdset);
+extern int parasite_cure_seized(struct parasite_ctl *ctl);
+extern struct parasite_ctl *parasite_infect_seized(pid_t pid, int pid_dir,
+						   struct list_head *vma_area_list);
 
 #endif /* PARASITE_SYSCALL_H_ */

include/ptrace.h

@@ -37,6 +37,7 @@ extern int seize_task(pid_t pid);
 extern int unseize_task(pid_t pid, enum cr_task_state st);
 extern int ptrace_peek_area(pid_t pid, void *dst, void *addr, long bytes);
 extern int ptrace_poke_area(pid_t pid, void *src, void *addr, long bytes);
+extern int ptrace_swap_area(pid_t pid, void *dst, void *src, long bytes);
 extern int ptrace_show_area(pid_t pid, void *addr, long bytes);
 extern int ptrace_show_area_r(pid_t pid, void *addr, long bytes);
 

ptrace.c

@@ -175,3 +175,21 @@ err:
 	return -2;
 }
 
+/* don't swap big space, it might overflow the stack */
+int ptrace_swap_area(pid_t pid, void *dst, void *src, long bytes)
+{
+	void *t = alloca(bytes);
+
+	if (ptrace_peek_area(pid, t, dst, bytes))
+		return -1;
+
+	if (ptrace_poke_area(pid, src, dst, bytes)) {
+		if (ptrace_poke_area(pid, t, dst, bytes))
+			return -2;
+		return -1;
+	}
+
+	memcpy(src, t, bytes);
+
+	return 0;
+}